GPS systems play an important role in the marine environment. The basic function is to determine the coordinates of the vessel's present location. These coordinates then allow the user to pinpoint their position on a map or chart of the waterways.
Because waterways change and the methods of creating the cartography is becoming more exact, paper charts are quickly becoming obsolete. Most marine GPS systems now include built-in electronic cartography. This cartography feature is either embedded in the memory of the system or is available on a portable media format (e.g., memory card, CD, etc.). Once the GPS system knows the vessel's present location and has electronic cartography available, it is able to show the present location of the vessel on the system's displayed map. This allows the vessel operator to use the GPS system as a navigational aide.
Some versions of electronic cartography also include water depth information. Here, the water depth is associated with the actual GPS coordinates that make up the chart. Instead of the chart showing the water depth for every available coordinate on the map, the charts use what are known as depth contour or bottom contour lines. These lines are shown periodically in depth increments, such as every 1 foot or every 10 feet or every 100 feet, depending on the actual contour of the bottom and the accuracy of the measurement methods used when creating the cartography. These depth contour lines will follow the depth associated with the line so as the waterway bottom comes up or down these lines will shift accordingly.
Vessel navigation through GPS has evolved from its earlier days in locating the vessel upon a body of water and displaying that location information for a vessel operator to an ability to create user programmed routes to guide the vessel. Conventional GPS allows users to manually create a series of turn points and then connect them together to create a contiguous path for the vessel to follow. Unfortunately, disadvantages exist with conventional GPS. As an example, one disadvantage is that it is cumbersome and, depending on the detail provided by the underlying chart, may not be truly accurate. Additionally, a certain amount of time is generally required to create the turn points necessary to generate a desired route, making it difficult to generate such a route while the vessel is underway.
In conventional GPS systems, the charts, codes, programs and systems typically have limited resources available for processing and converting complex chart and depth contour information. For example, a fishing vessel may be in the vicinity of a desirable depth for fishing, but will typically traverse among various due to an inability to maintain a course in which the depth of the water below the boat is fairly constant.
As such, there exists a need for a system which can automatically create a navigable route along a specific depth contour line depicted on a GPS or other visual display. Embodiments of the invention provide such a system. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.